"It grieves me to make this announcement," park superintendent Sarah Craighead said in a statement. "A northern long-eared bat, showing symptoms of white-nose syndrome, was found in Long Cave in the park. The bat was euthanized on January 4 and sent for laboratory testing. Those tests confirmed white-nose syndrome."

Long Cave is the park's longest bat hibernaculum, providing a home for endangered gray and Indiana bats as well as other, more common species. It's not connected to Mammoth Cave itself, so National Park Service officials have no plans to suspend tours of the 390-mile hollow, known as the world's longest cave system. Long Cave is undeveloped, the NPS notes, and hasn't been open to visitors for more than 80 years.

White-nose syndrome was unknown to science before 2006, when it appeared suddenly at a bat cave in New York state. It has since roared across the Eastern Seaboard, spreading into 21 states and four Canadian provinces. The disease is named after a bizarre white fuzz that grows on the nose, ears and wings of infected bats. Other symptoms include awaking too early from hibernation and flying around outside during winter, when food is scarce or nonexistent. In some bat populations, the mortality rate can be as high as 100 percent.

The disease's origins were mysterious until 2011, when scientists finally linked it to a previously unknown fungus, Geomyces destructans, that may be an invasive species from Europe. Although white-nose syndrome spreads primarily from bat to bat, humans may also inadvertently carry around G. destructans spores on their shoes, clothing or caving gear, so authorities often try to slow down the epidemic by closing caves.

The spread of white-nose syndrome since 2006. Click map to enlarge. (Image: U.S. FWS)

Mammoth Cave National Park has more than 400 individual caves, all of which are closed to human access except for ranger-led tours and authorized research trips. But some 400,000 tourists still participate in the park's Mammoth Cave tours every year, generating at least $3 million annually in visitor fees, so long-term closures aren't a simple decision. It's also unclear if they would be effective, since white-nose syndrome apparently infiltrated Long Cave even though tourists aren't allowed there.

Park officials at least weren't caught off-guard by this news. Since white-nose syndrome had already been reported in nearby areas, the park adopted decontamination procedures — namely turf mats that remove spores from visitors' shoes — more than two years ago. And with such precautions in place, Craighead says cave tours can even be beneficial, since they give park staff a chance to teach captive audiences about the problem.

"About 400,000 people tour Mammoth Cave each year, providing an excellent opportunity for us to educate the public about the importance of bats and the disease," she says. "We screen all visitors before they go on a cave tour and visitors walk across decontamination mats as they exit their tours."

The species that tested positive for white-nose syndrome at Long Cave was a northern long-eared bat, but the NPS says all nine of the park's cave-dwelling species are susceptible to the disease, including endangered gray and Indiana bats. Wildlife experts have long warned G. destructans is on pace to wipe out some entire bat species, which could be a disaster both for local ecosystems and economies.

Bats help regulate a variety of insect populations, suppressing disease-spreading bugs like mosquitoes as well as many agricultural pests. By some estimates, bats save the U.S. agriculture industry at least $3 billion per year, or about $74 per acre for the average farmer. According to the U.S. Geological Survey, all the bats killed so far by white-nose syndrome could have eaten up to 8,000 tons of insects per year.

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